Build an EWE Receive Antenna
The EWE is a small, terminated receive antenna purpose-built for one job: cutting through noise and interference on the crowded low bands so you can actually hear weak DX. It has no meaningful gain and is not a transmit antenna — its value comes entirely from a directional pattern with a useful front-to-back ratio, packed into a footprint of just a few feet on a side. This guide covers the complete build from element dimensions through the feedpoint transformer, termination resistor, and TX/RX switching.
Two Vertical Elements, One Top Wire, One Resistor
The EWE consists of two vertical wire sections ("posts") connected by a horizontal top wire, forming a squared-off "U" shape. One post's base connects to a termination resistor to ground; the other post's base connects to a feedpoint transformer that steps the antenna's very low impedance up to something a 50Ω receiver input can use. The whole structure is physically tiny compared to a wavelength on 160m or 80m — its directivity comes from the phase relationship between the two vertical elements, not from aperture size.
The Termination Resistor — Found Empirically
As with this site's K9AY loop, the termination resistor value is the most important variable in the whole design, and it is not a fixed textbook number — it depends on your antenna's exact dimensions and your local ground conductivity. Published starting values (commonly in the 800-950Ω range) are a starting point for experimentation, not a guaranteed final answer.
Why This Isn't a Transmit Antenna
The termination resistor dissipates a meaningful fraction of any power applied to the antenna as heat, and small receive-only components (the feedpoint transformer core, the resistor itself, thin wire gauge) are not rated for transmitter power levels. Applying even modest transmit power to an EWE risks destroying the termination resistor and the feedpoint transformer, and provides no meaningful radiated signal in return — this is purely a receive tool, always switched out of circuit before transmitting.
- TX/RX relay is mandatory: a relay that physically disconnects the EWE from the receiver (and ideally grounds the receive line) during transmit protects both the antenna and your receiver's front end from your own transmitted power.
- Separate from your transmit antenna: the EWE is a completely separate system used alongside a normal transmit antenna, switched in only when receiving.
Feedpoint Transformer
Because the EWE's own impedance is very low (a handful of ohms), a step-up transformer is required to present a reasonable match to 50Ω coax — the same approach used across this site's other small receive antennas.
| Band | Post height | Post spacing | Starting termination resistor |
|---|---|---|---|
| 160m | 10-12 ft | 14-16 ft | ~950 Ω starting point |
| 80m | 8-10 ft | 12-14 ft | ~850 Ω starting point |
| 40m | 8 ft | 10-12 ft | ~800 Ω starting point |
EWE Antenna Starting-Point Calculator
Materials for a complete EWE build
Building the EWE Receive Antenna
This is a small, low-cost build — most of the effort is in the termination resistor optimization step, not the physical construction.
Install the Two Support Posts
Set the two fiberglass support poles at the spacing from the dimensions table, oriented so the antenna's favored direction (toward the feedpoint end, away from the termination end) points at your target listening direction.
Run the Vertical and Top Wires
Run a wire up each post, connected across the top by a horizontal wire, forming the squared-off "U" shape. Keep the wire taut but not over-tensioned on the fiberglass poles.
Install the Termination Resistor and Ground
At the base of the termination post, connect a variable resistor (for initial testing) between the wire and a ground rod driven at that location.
Install the Feedpoint Transformer
At the base of the feedpoint post, wind and install the 9:1 unun on the ferrite toroid, connecting the antenna wire to the transformer's high-impedance side and the coax to the low-impedance (50Ω) side.
Install the TX/RX Relay
Wire the relay so it disconnects the EWE's coax from the receiver whenever your station keys up, and connects it back for receive.
Route Coax to the Shack
Run the receive coax from the feedpoint enclosure to your receiver, ideally with a low-noise preamplifier given this antenna's inherently low signal capture.
Optimize the Termination Resistor
Using a known station in the "back" direction (behind the antenna's favored direction), adjust the variable termination resistor while listening, seeking the setting that minimizes signal from the back while keeping the front strong. Once found, measure the variable resistor's value and replace it with a fixed resistor of that value.
| Symptom | Most likely cause | Diagnosis | Fix |
|---|---|---|---|
| No directional effect at all — sounds omnidirectional | Termination resistor missing, wrong value, or poor ground connection | Check the resistor value and ground rod connection at the termination post | Verify and correct the ground connection; re-optimize the resistor value |
| Very weak signals on all directions | Feedpoint transformer wiring reversed, or normal expected low output | Check transformer winding sense against the reference diagram | Correct transformer wiring if reversed; otherwise add a low-noise preamp, which is normal for this antenna class |
| Front-to-back ratio much worse than expected | Termination resistor not optimized for your specific site | Re-run the optimization procedure using a known back-direction station | Adjust the resistor value; ground conductivity differences between sites are the most common cause |
| Antenna damaged after operating | Transmitter power reached the EWE, likely a relay or switching fault | Check relay operation and switching timing relative to transmit keying | Repair or replace the relay; verify switching happens before RF is applied |
| Noise floor didn't improve versus the transmit antenna | EWE oriented in the wrong direction, or not actually switched in | Confirm antenna orientation and relay switching state while receiving | Reorient toward the desired null direction; verify the switch/relay state |
Can I transmit through this antenna if I keep the power low?
No. This is a receive-only design — the termination resistor, feedpoint transformer, and thin wire are not built to handle transmit power at any level, and the antenna provides no meaningful radiated signal in return even if it survived. Always switch to a separate transmit antenna before keying up.
Why is my received signal so much weaker than on my regular antenna?
This is completely normal and expected — the EWE has essentially no gain (often significantly negative in dBi terms). Its entire value is the directional pattern that reduces unwanted noise and interference, not signal strength. Pair it with a low-noise preamp if the raw signal level is too low for comfortable listening.
How is this different from a K9AY loop?
Both are small terminated receive antennas relying on a critical termination resistor, but the EWE's rectangular "U" shape and typical dimensions differ from the K9AY's triangular loop geometry. Both target similar performance goals (directional low-band receive) with different specific constructions.
Can I build multiple EWEs for different directions?
Yes — this is a common approach, switching between two or four EWEs aimed at different headings from a single control box at the operating position.
Do I need a preamp with this antenna?
Most operators find a low-noise preamp genuinely useful given how little signal a small terminated loop like this captures compared to a full-size transmit antenna, especially on a quiet receiver front end.
Does the resistor value change between day and night?
The optimum value is set primarily by the antenna's physical dimensions and local ground conductivity, which don't change with time of day — but propagation changes can make it seem like the "best" null shifts, so many operators optimize during their typical operating hours rather than at an arbitrary time.